Many studies have demonstrated that the cerebellum receives auditory inputs. Cerebellar neurons responding to sound stimuli have been reported in cats, rats, monkeys and bats. With the exception of bats, cerebellar auditory neurons have only been isolated from the cerebellar vermis. In bats, auditory representation in the vermis and hemispheres has been studied. Species-specific differences in basic response properties have been described. It has been suggested that in sound localization, the cerebellum plays an important role in orienting an animal toward a sound source. However, directional response characteristics of cerebellar neurons to sound stimulation have not been well studied. How the cerebellar neurons code a moving sound and how the auditory space may be represented in the cerebellum have not been studied. The question of how cerebellar neurons may be related with sound emission has not been investigated either. The specific aims of this research proposal are to conduct electrophysiological studies to answer the following two major questions. 1) How do cerebellar neurons code directional information of a sound source? 2) What are the cerebellar activity during sound emission? The data obtained from this proposed research will contribute to our understanding of cerebellar function in bat echolocation behavior in particular, and to provide new insight on cerebellar function in general. Specifically, they may reveal the mechanism of coding of a sound stimulus by the cerebellar neurons and how the auditory space is registered in the cerebellum. The study of cerebellar activity during sound emission may reveal clues as how the cerebellum may regulate the activity of the motor pathways for vocalization. As the cytoarchitecture of the cerebellum of a bat, which will be used in this proposed research, is basically the same as that of a human, such data will undoubtedly contribute to the advancement of basic knowledge of our own cerebellum physiology.